THE MEDUSA. 15 



left the parent receptacles, they have all eight tentacula 

 (fig. 16,) and from three to five new ones begin to 

 appear, and the older ones when extended, have already 

 attained a length of from three to five times that of the 

 body (fig. 17.) In this way the nmiiber of these organs 

 continues to increase during the growth of the animal, 

 and new ones are constantly springing up in the inter- 

 spaces of the older ones, so that at length the number of 

 tentacula amounts to 24 — 28 — 30. From the size of a 

 small grain of sand the body becomes about a line in 

 length, and the original brownish colour passes gradually 

 through a reddish gray to a transparent grayish white. 



In this fixed condition the animal in its external form 

 very much resembles a polype, but it now, although 

 unable to move about in the water, approaches the 

 Medusa form much nearer than when in the infusory 

 form it swam about by means of cilia. 



This polypiform animal, which we shall afterwards con- 

 sider as a pedunculated Medusa, is affixed at the bottom of 

 the sea on various substances, as stones, or the shells of con- 

 chifera, but especially, as it would seem, on the stalks of the 

 large Laminaria. When the animal has obtained its full 

 number of arms or tentacula, or, as it may be expressed, 

 has reached its full growth, but a short time elapses 

 before a new life commences in it. Transverse ^^^inkles 

 are formed around the body, which increases at the same 

 time considerably in size, especially in length, and thence 

 assumes a cylindrical form. These transverse "wrinkles 

 appear at first towards the superior extremity and thence 

 gradually descend, retaining, however, always the same 

 distance from each other ; they are at first faintly marked, 

 and more like transverse lines or rings surrounding the 

 body (figs. 20, 21 ;) by degrees, however, the wrinkles or 

 fiu-rows become manifestly deeper and deeper, in the still 

 elongating body, and at the same time the superior 

 margin of the projecting portions which are separated by 

 the furrows, becomes more and more elevated and 

 presents eight distinct lobes or divisions, which are placed 



